Propeller are currently used to ensure propulsion and lift on machines themselves and in generators to convert the power output of a fluid into electrical energy.
The use of counter-rotating propellers has the advantage that they develop only a minimal reverse torque reaction on their supporting structure or frame, which is not the case for monopropeller machines.
The differences between two coaxial propellers are due to the fact that the kinematic fluid characteristics change for the downstream propeller with each passage of the upstream propeller. Until now, possible solutions for reducing the difference in torque between the two propeller wheel hubs were as follows:
independent control of blade pitch PA0 different and predetermined rotational speeds PA0 use of unequal diameters PA0 spacing between rotational planes PA0 appropriate choice of blade spin
Such stopgap measures, employed separately or jointly, only serve to displace the problem of wheel hub torque to the engine itself by resorting to empirical solutions and complex mechanisms.
French Patent No. 1,497,099 describes (in its second part) a mechanism designed to automatically ensure balanced torque on counter-rotating propellers through the adaptation/application of a differential composed of one input and two output shafts, such as the type applied to automobile axles. In other words, it is composed of a conventional differential with conical pinons, of which one of the output shafts is inversed and co-axially aligned to the other shaft through a series of conical pinons wherein the fixation of the intermediate pinion is indispensable to the counter-rotative function of the second output shaft.
French Patent Application No. 2,406,565 describes the same mechanism, which comprises an input shaft perpendicular to the axis of the counter-rotating hub, and wherein the inversing transmission gears are either internal or external.